M/C help about genetics part 2?

1)in birds, sex is determined by a ZW chromosomes scheme. Males are ZZ and females are ZW. A lethal recessive allele that causes death of the embryo occurs on the Z chromosom in pigeons. what would be the sex ratio in the offspring of a cross between male heterozygous for the lethal allele and a normal female?


a)2:1 male to female


b)1:2


c)1:1


d)4:3


e)3:1





2)if inheritance of a human trait is sex-linked and reccessive, any could result EXCEPT


a)expression of the trait might skip a generation


b)the trait could be more common in females than males


c)all females might become homozygous for the trait


d)the gene fot the trait might mutate to a dominate allele





3)if protiens were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides?


a)1


b)2


c)3


d)4


e)12

M/C help about genetics part 2?
1) c, 2) b, 3) b